Method for selective fabrication of high capacitance density areas in a low dielectric constant material and related structure are disclosed. In one embodiment, a first area of a dielectric layer is covered, for example with photoresist, while a second area of the dielectric layer is exposed to a dielectric conversion source such as E-beams, I-beams, oxygen plasma, or an appropriate chemical. The exposure causes the dielectric constant of the dielectric layer in the second area to increase. A number of capacitor trenches are etched in the second area of the dielectric. The capacitor trenches are then filled with an appropriate metal, such as copper, and a chemical mechanical polish is performed. The second area in which the capacitor trenches have been etched and filled has a higher capacitance density relative to the first area. In another embodiment, the exposure to the dielectric conversion source is not performed until after the chemical mechanical polish has been performed. In yet another embodiment, a blanket layer of metal, such as aluminum, is first deposited. The blanket layer of metal is then etched to form metal lines. Then a gap fill dielectric is utilized to fill the gaps between the remaining metal lines. A first area of the gap fill dielectric is then covered and a second area of the gap fill dielectric is exposed to a dielectric conversion source. After exposure to the dielectric conversion source, the dielectric constant of the gap fill dielectric in the second area increases. The metal lines in the second area can then be used as capacitor electrodes of a high density capacitor.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method comprising steps of: etching a plurality of interconnect trenches in a first area in a dielectric layer and etching a plurality of capacitor trenches in a second area in said dielectric layer, said dielectric layer comprising a low dielectric constant material; covering said first area in said dielectric layer, said dielectric layer having a first dielectric constant; exposing said second area in said dielectric layer to a dielectric conversion source so as to increase said first dielectric constant of said dielectric layer in said second area to a second dielectric constant.
2. The method of claim 1 wherein said covering step comprises covering said first area in said dielectric layer with photoresist.
3. The method of claim 1 wherein said low dielectric constant material is hydrogen silsesquioxane.
4. The method of claim 1 further comprising a step of filling each of said plurality of capacitor trenches and each of said plurality of interconnect trenches with metal after said etching step and prior to said covering step.
5. The method of claim 4 wherein said metal is copper.
6. A method comprising: forming a dielectric layer in a semiconductor die, said dielectric layer having a first dielectric constant, said dielectric layer comprising a low dielectric constant material; covering a first area of said dielectric layer; exposing a second area in said dielectric layer to a dielectric conversion source so as to increase said first dielectric constant of said dielectric layer in said second area to a second dielectric constant; etching a plurality of interconnect trenches in said first area in said dielectric layer; etching a plurality of capacitor trenches in said second area in said dielectric layer; filling said plurality of interconnect trenches and said plurality of capacitor trenches with metal; wherein said plurality of capacitor trenches form a composite capacitor.
7. The method of claim 6 further comprising a step of performing a chemical mechanical polish after said filling step.
8. The method of claim 6 wherein said metal is copper.
9. A method comprising: forming a dielectric layer in a semiconductor die, said dielectric layer having a first dielectric constant, said dielectric layer comprising a low dielectric constant material; etching a plurality of interconnect trenches in a first area in said dielectric layer; etching a plurality of capacitor trenches in a second area in said dielectric layer; filling said plurality of interconnect trenches and said plurality of capacitor trenches with metal; performing a chemical mechanical polish on said first and second areas; exposing said second area in said dielectric layer to a dielectric conversion source so as to increase said first dielectric constant of said dielectric layer in said second area to a second dielectric constant; wherein said plurality of capacitor trenches form a composite capacitor.
10. The method of claim 9 wherein said metal is copper.
11. A method comprising: depositing a metal layer in a semiconductor die; etching said metal layer to form a plurality of interconnect lines in a first area of said semiconductor die and a plurality of capacitor electrodes in a second area of said semiconductor die; depositing a gap fill dielectric between said plurality of capacitor electrodes and between said plurality of interconnect lines, said gap fill dielectric comprising a low dielectric constant material; covering said first area in said gap fill dielectric, said gap fill dielectric having a first dielectric constant; exposing said second area in said gap fill dielectric to a dielectric conversion source so as to increase said first dielectric constant of said gap fill dielectric in said second area to a second dielectric constant; wherein said plurality of capacitor electrodes form a composite capacitor.
12. The method of claim 11 wherein said covering step comprises covering said first area in said gap fill dielectric with photoresist.
13. The method of claim 11 wherein said dielectric conversion source comprises E-beams.
14. The method of claim 11 wherein said dielectric conversion source comprises I-beams.
15. The method of claim 11 wherein said dielectric conversion source comprises an amine based chemical.
16. The method of claim 11 wherein said dielectric conversion source comprises oxygen plasma.
17. The method of claim 11 wherein said low dielectric constant material is hydrogen silsesquioxane.
18. The method of claim 11 wherein said metal layer comprises aluminum.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 22, 2004
September 19, 2006
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